Oregon State University engineers have applied new coatings on anodes of microbial electrochemical cells, which heightens their electricity production by 20 times, and is another step closer to producing electricity from sewage.

The graphite anodes were coated with palladium at one point in order to produce electricity, but that didn't produce quite as much as the nanoparticle layer of gold, which is what increased the electricity production by about 20 times. This is a huge advance toward technology that could both produce levels of electricity and clean biowaste at the same time, ultimately changing the face of renewable energy and wastewater treatment. Also, this sort of technology could help treat wastewater in developing nations where an inadequate power supply prevents proper treatment.

During the course of these experiments, researchers inserted bacteria from sewage into an anode chamber and allowed it to form a biofilm, absorb nutrients and grow. The bacteria releases electrons during this process and fuels electricity production.

"This is an important step toward our goal," said Frank Chaplen, an associate professor of biological and ecological engineering. "We still need some improvements in design of the cathode chamber, and a better understanding of the interaction between different microbial species. But the new approach is clearly producing more electricity."

In addition, researchers have reason to believe that an iron nanoparticle coating would increase the electrical output of sewage as much as the layer of gold in some types of bacteria. Also, a "similar approach" could produce hydrogen gas rather than electricity, which could lead to further advancements in hydrogen fuel cell technology for cars as well as treating wastewater.

"Recent advances in nanofabrication provide a unique opportunity to develop efficient electrode materials due to the remarkable structural, electrical and chemical properties of nanomaterials," said the published research paper. "This study demonstrated that nano-decoration can greatly enhance the performance of microbial anodes."

While more research is required to lower costs and improve efficiency, researchers say this technology has been proven in the laboratory. The study was led by Hong Liu, an assistant professor of biological and ecological engineering, and was published in Biosensors and Bioelectronics.